This application is related to and claims priority from Japanese Patent Applications No. 2000-20073 filed on Jan. 28, 2000, No. 2000-95021 filed on Mar. 30, 2000, No. 2000-264860 filed on Sep. 1, 2000, and No. 2000-339037 filed on Nov. 7, 2000, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a vehicle air conditioning system including a space air conditioning unit that introduces conditioned air into a passenger compartment, and a seat air conditioning unit that introduce air into a vehicle seat.
2. Description of the Related Art
In a conventional vehicle air conditioning system disclosed in JP-A-10-297243 corresponding to U.S. Pat. No. 6,079,485, a seat air conditioning unit and a space air conditioning unit are provided. Further, a control unit is provided to change an operating condition or a set information of the space air conditioning unit based on a seat temperature of a vehicle, an operating condition of the seat air conditioning unit or a set information of the seat air conditioning unit. The control unit uses a seat set temperature for the seat air conditioning unit as a set temperature for the space air conditioning unit so that an air conditioning operation of a passenger compartment is performed.
Conversely, in a vehicle air conditioning system, a control unit is provided to change an operating condition or a set information of a seat air conditioning unit based on an operating condition or a set information of a space air conditioning unit. This control unit uses a set temperature for the space air conditioning unit as a seat set temperature for the seat air conditioning unit so that an air conditioning operation of a vehicle seat is performed. Specifically, both the space and seat air conditioning units operate in the same operation condition using one set information (e.g., one side set temperature). When the one set information for one of the space and seat air conditioning units is changed, the other set information of the other unit is changed.
However, when an air conditioning load on the space air conditioning unit is large, the seat air conditioning unit is operated with a large capacity on the basis of the set temperature of the space air conditioning unit. Therefore, the seat air conditioning unit exercises an excessively high air conditioning ability in a steady state. Consequently, the seat is cooled excessively in summer and is heated excessively in winter, and an uncomfortable feeling may be given to a passenger on the vehicle seat.
The foregoing problem is serious with a vehicle air conditioning system in which a seat air conditioning unit uses warm air or cool air supplied from a space air conditioning unit for seat heating or seat cooling. Even if an air temperature level of the space air conditioning unit is in a steady state, an air temperature level (thermal sensation level) of the seat air conditioning unit is liable to be excessively low or excessively high, and therefore, an uncomfortable feeling may be given to a passenger on the vehicle seat. Consequently, while the air conditioning system is in a heating mode in winter, the passenger""s face will be flushed by warm air.
When the set information for the seat air conditioning unit is changed, the set information for the space air conditioning unit changes accordingly. Therefore, the space air conditioning unit is unable to create a properly air conditioned atmosphere for a passenger seated on a seat not provided with the seat air conditioning unit, and an uncomfortable feeling may be given to the passenger on this seat.
In view of the foregoing problems, it is an object of the present invention to provide a vehicle air conditioning system capable of achieving comfortable space air conditioning performance and comfortable seat air conditioning performance conforming to passenger""s temperature feeling regardless of season.
It is an another object of the present invention to provide a vehicle air conditioning system having a seat air conditioning unit provided in a vehicle seat, which can maintain a set thermal sensation level of a seat surface set by a passenger on the vehicle seat even when an air conditioning state of a passenger compartment is changed.
It is a further another object of the present invention to provide a vehicle air conditioning system having a seat air conditioning unit provided in a vehicle seat, which can maintain an air conditioning state of a passenger compartment desired by a passenger on an another vehicle seat where the seat air conditioning unit is not provided, even when a passenger on the vehicle seat where the seat air conditioning unit is provided changes a thermal sensation level of a seat surface.
According to the present invention, in a vehicle air conditioning system having a space air conditioning unit and a seat air conditioning unit, a control unit controls the space air conditioning unit and the seat air conditioning unit in accordance with a detection value of a thermal load of the vehicle. The control unit includes space calculation means for calculating a space target air temperature to be blown into the passenger compartment based on the detection value of the thermal load of the vehicle and a set temperature set by a passenger, space controlling means for controlling the space air conditioning unit in accordance with a space control value calculated based on the space target air temperature, and seat controlling means for controlling the seat air conditioning unit in accordance with a seat control value calculated based on the space target air temperature. Further, the seat controlling means includes first seat air conditioning means which determines the seat control value in a steady air-conditioning state of the passenger compartment, and second seat air-conditioning means which determines the seat control value in a transition air-conditioning state of the passenger compartment. Accordingly, in the vehicle air conditioning system, comfortable space air conditioning performance of the passenger compartment and comfortable seat air conditioning performance conforming to passenger""s temperature feeling can be obtained regardless of season.
Preferably, the space control value of the space controlling means is set based on the space target air temperature in such a manner an air amount blown into the passenger compartment is increased when the space target air temperature is lower than a first predetermined value or is higher than a second predetermined value higher than the first predetermined value, and the seat control value of the first seat air conditioning means is set based on the space target air temperature in such a manner that an air amount blown into the seat through the seat air conditioning unit is decreased when the space target air temperature is lower than the first predetermined value or is higher than the second predetermined value. Accordingly, when the space target air temperature is lower than the first predetermined value, that is, when a difference between the set temperature and temperature of air blown into the passenger compartment becomes larger, the air amount blown into the passenger compartment is made larger as the temperature of air blown into the passenger compartment is lower. However, the air amount blown from a seat surface of the seat is made smaller as the temperature of air blown into the passenger compartment is lower. Thus, super-cooling for a passenger on the seat can be prevented in cooling operation where the space target air temperature is lower than the first predetermined value. Similarly, super-heating for the passenger on the seat can be prevented in heating operation where the space target air temperature is higher than the second predetermined value.
Preferably, the control unit has air-conditioning state determining means for determining whether or not an air conditioning state of the passenger compartment is in the steady air-conditioning state or in the transition air-conditioning state, and the air-conditioning state determining means determines the steady air-conditioning state or the transition air-conditioning state by a steady state discrimination based on the set temperature and an inside air temperature among the detection value of the thermal load. Accordingly, the steady air-conditioning state or the transition air-conditioning state can be accurately determined.
Preferably, the control unit includes air-conditioning switching control means which gradually changes the seat control value from a value corresponding to the transition air-conditioning state to a value corresponding to the steady air-conditioning state, at an initial time of the steady air-conditioning state, immediately after the transition air-conditioning state. Therefore, even in the initial time of the steady air-conditioning state immediately after the transition air-conditioning state, it can restrict an unpleasant feeling from being given to the passenger on the seat.
Further, the seat air conditioning unit includes a seat air conditioning case defining a seat air passage through which at least one of conditioned air from the space air conditioning unit and inside air from the passenger compartment flows toward a seat surface of the seat, a seat temperature changing member which changes temperature of air blown from the seat surface through the seat air passage, a seat blower disposed in the seat air passage for generating an air flow in the seat air passage toward the seat surface, and a seat temperature setting member which sets a thermal sensation level of the seat surface to a desired thermal sensation level. The control unit has operation state determining member for determining an operation state of the passenger compartment, and the control unit controls the seat temperature changing member and the seat blower to obtain the desired thermal sensation level of the seat surface, in the operation state of the space air conditioning unit. Because the control unit controls the seat temperature changing member and the seat blower to obtain the desired thermal sensation level of the seat surface, an unpleasant feeling is not given to a passenger on the vehicle seat. Accordingly, a set thermal sensation level of the seat surface set by the passenger on the vehicle seat can be maintained even when an air conditioning state of the passenger compartment is changed. Further, even when the thermal sensation level of the seat surface is changed in accordance with a passenger""s request, air-conditioning capacity of the space air conditioning unit is not changed. Accordingly, the air conditioning state of the passenger compartment desired by a passenger on an another vehicle seat where the seat air conditioning unit is not provided can be maintained, even when the passenger on the vehicle seat where the seat air conditioning unit is provided changes the thermal sensation level of the seat surface.